1. Field of the Invention
The present invention relates to a data filter, and more particularly, to a one-dimensional signal adaptive filter for reducing blocking noise, and a one-dimensional signal adaptive filtering method.
2. Description of the Related Art
Generally, picture encoding standards such as MPEG of the International Standardization Organization (ISO) and H.263 recommended by the International Telecommunication Union (ITU) adopt block-based motion estimation and discrete cosine transform (DCT) of blocks. When an image is highly compressed, the block-based coding may cause the well-known blocking effect. A typical blocking effect is grid noise in a homogeneous area in which adjacent pixels have relatively similar pixel values. Another blocking effect is staircase noise which has a staircase shape and is generated along the edges of the image.
Grid noise shows traces of the block-based process at the edges between blocks when the compressed data is displayed on a screen after being restored. Thus, one can identify the edges between blocks. Also, staircase noise has a staircase shape at the edges of the image, so that one can notice a bumpy edge on the image.
In order to reduce the blocking effect occurring when block-based coding is performed, several methods have been suggested. According to H.261 encoding, a simple 3.times.3 low pass filter (LPF) is used as a loop filter to reduce the blocking effect. However, when using the 3.times.3 LPF, the extent to which the blocking effect can be removed is limited and the amount of calculation required is increased.